Two types of QSFP28 cables are available: one is a high-speed cable with QSFP28 connectors on either end that can send and receive 100Gbps data over a thin twinax cable or a fiber optic cable, and the other is a breakout cable that can divide a single 100G signal into four 25G or two 50G signals (QSFP28 to SFP28). This allows network devices with different speed ports to be connected while utilizing all available port bandwidth.
Many 100G passive DAC types
The two main types of 100G DAC cables are 100G Active DAC and 100G Passive DAC. Additionally, there are three different types of 100G passive DAC: 100G QSFP28 to 100G QSFP28 Passive DAC, 100G QSFP28 to 4 25G SFP28 Passive DAC, and 100G QSFP28 to 2x 50G QSFP28 Passive DAC.
Passive DAC 100G QSFP28 to 100G QSFP28
A 4-channel parallel passive copper connection called the 100G QSFP28 to 100G QSFP cable, integrates four 28 Gbps SFP channels into a single high-density cable. It provides a cost-effective method of establishing a 100-Gigabit link between QSFP-100G ports of switches within racks and across adjacent racks, making it ideal for data centers, high-end servers, and enterprise wiring closets. It offers 4 independent data transmitting channels and 4 independent data receiving channels via copper cable.
4x 25G SFP28 passive DAC cables, 100G QSFP28
A breakout cable called a 100G QSFP28 to SFP28 Passive DAC Cable offers a hybrid transition from four separate SFP28s at one end to a QSFP28 at the other. It provides four parallel, bi-directional channels, each with a maximum 25Gbps speed. The 100G to 25G breakout cable satisfies the rising need for increased channel densities with high-level signal integrity in high-performance computing, top-of-rack switching, and network storage installations thanks to its minimal crosstalk, short bend radius, and low power consumption.
2x 50G QSFP28 passive direct attach cables, 100G QSFP28
A 4-channel parallel copper direct attach cable that offers 4 separate data transmission channels and 4 independent data receiving channels is known as a 100G QSFP28 to 2x 50G QSFP28 breakout DAC. This gadget can transmit data at a total rate of 100Gbps across a 5m distance. This QSFP28 cable is appropriate for the Infiniband EDR and 128G Fiber Channel and was created for usage in a cost-effective 100GbE to 2 x 50GbE Ethernet connection solutions to fulfill the rising requirements for increased bandwidth in data centers.
Main source: https://fibermart.livejournal.com/
